Nickel plating bath containing acetylenic polyamines



nite ttes Ptent NICKEL PLATING BATH CONTAINING ACETYLENIC PGLYAMTNES Fred 1. Nobel, North Valley Stream, and Barnet D. Ostrow, North Bellmore, N. Y., assignors to Elechem Corp., Jersey City, N. L, a corporation of New Jersey No Drawing. Application .Ianuary 21, 1955 Serial No. 483,419

8 Claims. (Cl. 204--49) The present invention is directed to bright nickel plating baths and more particularly to the use of an improved agent in a normal type of nickel bath to improve the brightness of platings made therefrom.

In the past it has been customary to electroplate bright nickel coatings and a considerable variety of addition agents to the usual nickel bath have been proposed. While such substances had some eflectiveness, they either were incapable of providing a completely bright deposit or if the deposits were bright, they were in brittle form,

particularly when the coating was of substantial thicka ness. Some of the brightening agents used, such as chlorine or bromine substituted aldehydes, reduced the throwing power of the nickel bath, tended to give deposits which were passive and difiicult to cover well with chromium and they also tended to be brittle where the deposits were relatively heavy. Also under conditions which made it necessary to replate the nickel, or to plate nickel over nickel, the deposits obtained from a bath containing the aldehyde type of addition agents, which are used in relatively high concentrations, the nickel plate tended to become passive, making an activating treatment necessary.

There was also suggested the use of alkyl polyamines, which were asserted to be effective in obtaining a high degree of brightness required by the trade. Such compounds were reacted with various substances such as acrylonitrile, epichlorhydrin, in order to increase their molecular weights. It has been found that such high molecular weight compounds have an adverse effect on the ductility of the deposit and in addition do not give full brilliance to the deposits. Although alkyl polyamines such as tuiethylene tetramine and tetraethylene pentamine give deposits of excellent ductility, such deposits do not have maximum brightness but tend to be hazy. When used in higher concentrations, brightness of the deposit is increased, but darkening of the coating results particularly in the low current density areas accompanied by a decrease in the ductility of the deposit.

The present invention is intended and adapted to overcome the difliculties and disadvantages inherent in prior compositions of the type described, it being among the objects of the present invention to provide a composition of a nickel bath containing certain substances whereby the coatings obtained therefrom are smoother than the basis metal.

It is also among the objects of the present invention to provide a composition of the type described which results in coatings of extreme brightness together with a high degree of ductility.

It is further among the objects of the present invention to provide a composition which is highly efiective and provides an improved bright deposit even in low current density areas.

The basis of the present invention is the use of cer- 2,836,549 Patented May 27, 1958 -phonic groups, the latter having the following general formula: R. In such compounds R represents OH, NH, NH and alkali metal. Compounds of this type are known in the prior art and they include sulphonates, sulphonamids and sulphonimids, such as are described in Schlotter Patent No. 1,972,693, Brown No. 2,191,813 and Lind 2,238,861.

There may also be added to the bath polyalkylene amines and condensation products of said polyalkylene amines with aldehydes, the polyalkylene amines having 2 to 12 amino groups and containing alkylene groups having from 1 to 6 carbon atoms, and there being present in the amines from 2 to' 10 such alkylene groups.

In particular the use of a mixture of the sulphur-containing compounds described above with the polyamine reaction products of acetylenic compounds overcomes the undesirability of the darkening previously encountered at low current densities of the prior compositions. At the sarne time, the present composition results in the highly desirable characteristic of ductility of the deposit. They have the further advantage of making the bath more tolerant to highconcentrations of the addition agent without any adverse effects on the ductility of the deposit, and they do not increase the passivity of the nickel plate over that obtained from the Watts type bath without addition agents.

The preparation of the acetylenic compounds is known and such preparation is described by Victor Wolfe in Annalen, vol. 576, 1952, pages 35 to 45.

The compounds according to the present invention probably have the following general formula:

wherein X is a radical taken from the class consisting of R-CEC and R|C(GH3)CEC in which R represents H and CH (CH n is a numeral from 0 to 10 and X is X or hydrogen. Thus it can be seen that the total number of carbon atoms making up the group heretofore referred to as X varies from 2 to 15.

The following substances are typical of the unsaturated or acetylenic compounds which are reacted with polyamines:

Propargyl chloride Propargyl bromide 3-01-3 -methyl-1-butyne 5-Br-3-methyl-4-pentyne-3-ol Various polyamines having relatively low and even relatively high molecular Weights may be reacted with the acetylenic compounds and the following illustrates the general character of the amines which may be used.

Ethylenediamine Diethylenetriamine Triethylenetetramine Tetraethylenepentamine Pentapropylenehexamine Poleythyleneamine 1200 Polyethylene-amine 1800 The following are examples which illustrate the manufacture of the reaction products used in the present invention.

' Example 1 7 I T 2,836,54 Q i i. 1

4 mols. of propargyl bromide are introduced drop by drop into 1 mol.. of triethylenetetramine, the reaction mass being cooled in order to avoid undue rise of'tem-' perature; As a result of the reaction, fumes-of hydrobromic. acid are evolved. After such evolution-ceases, the reaction mass is heated to about 60 C. to complete the reaction. The reaction product is N,N,N ,N propargyl' triethylenetetramine.

Example 2 mols. of 3-chloro-3-methyl-l-butyne are introduced into 1 mol. of tetraethylene pentamine. The mixture is gradually heated, preferably ona water bath, to about 90 C. in order to cause the reaction to proceed. Fumes of hydrochloric acid are evolved and the reaction proceeds without any further addition of heat since the reaction is exothermic. The product is most likely 3N,3N,3N ,3-rnethyl-l-butyne. tetraethylenepentamine Example 3 2 mols. of 5-bromo-3-methyl-4 pentyne-3-ol are incorporated into 1 mol. of diethylenetriamine and the mixture is heated to 80, whereupon the reaction starts and' proceeds to completion. Fumes of hydrobromic acid are evolved and the reaction is completed when such' evolution ceases. The product may be designated as 5N,5N,5N ,3-methyl-4-pentyne-3-ol diethylenetriamine In the course of the reaction, the acetylenic compound is attached to amino nitrogen, usually to one of the terminal nitrogen groups and one or morev of the internal nitrogen groups. .It is also possible that acetylenic radicals attach themselves to both of the terminal nitrogen groups.

It has been found that the best plating results are obtained when the molecular ratio of the acetylenic halide used in equivalent to the total'number of amino groups in the polyamine. For example, the reaction product of 1 mol. of ethylenediamine and 2 mols. of the acetylenic halide gives the optimum results and the reaction product I of 1 mol. of triethylenetetramine with 4 mols. ofthe acetylenic halide also gives the best results. While better results are obtained when all or most of the'NI-I groups are reacted with the acetylenic compounds, im-

proved operation is obtained even when'some of the NIL-I groups remain 'unreacted.

It'is also possible to .start with an acetylenic dihalide such as 3,5-dibromo-4 pentyne-3-ol. In this case only /2 mol. of the acetylenic dihalide is necessary for each amino group. The product resulting from this. reaction is most likely the following general formula.

' HNCzENCzHrNCzHrNH anionic-02o Eo-oomom on on It is to be understood that the acetylenic addition agents 7 which are used in accordance with the present invention are incorporated in the bath in conjunction with the sulphonic compounds set forth above, in accordance with the prior art, such compounds. including sulphonates, sulphonamids and sulphonimids. The use of such acetylenic compounds in the compositions described, not only improved the leveling characteristics of the plating bath but also do not adversely effect the covering power of the bath or the ductility of the deposit even when the amine therewith is present in an ounts'as much as six times the optimum concentration used intheprior art. In fact, there is a considerable improvement in the current density 4 characteristics of the plating bath when reaction products of polyamines and acetylenic compounds are used.

The standard bath in which the compounds of the present invention are introduced is illustrated by the following a formula: V V

NiSO .6H' O 300 NiCl .7H O H BO 45' Wetting agent .25

The amounts stated are in grams per liter. The wetting agents are the usual ones common in the art and include such compounds as sodium lauryl sulphate, sodiumtetradecyl sulphate, sodium ethyl hexylsulphate and sodium ectylsuipliate. The followingjare examples of compositions which are added to theabove described standard bath to obtain the beneficial results of the present inventron. I i

' Example 4' The conditions of the baths will vary within certain limits which are recognized as being suitable for the purpose. The pH of the various solutions varies from approximately 3.0 to 4.2 and the temperatures'ofthe. baths vary from about 130 F. to 170 F.. Excellent platings which are highly ductile and of extreme bright-'2.

ness are obtained thereby. The nickel salts used in the bath may be replaced in whole or in part by other soluble salts thereof, such as sulpharnate, fiuoborate, and the Weights of like. The polyamines may have molecular. say, 1200 to 1800 with good results. i We claim:;

1. In a nickel plating bath comprising an aqueous solution of a compound taken from the classcon'sisting of nickel sulfate and nickel chloride, the improvement which comprises the addition of the reaction productof a soluble acetylenic compound having from 2 to 15 carbon atoms and taken frorn the class consisting of acety lenic halides and acetylenic alcohol halides, with an 1 alkylene polyamine having 2 to 12 amino groups, the alkyl ene groups having 2 to 3 carbon atoms, said soluble acetylenic compound being present in an amount of from .001 g./l. to 1.0 g./l., said product containing at least one carbon-to-carbon triple bond and being an acetylenic polyamine.

2.' A nickel plating bath according to claim 1 wherein v there is added to saidbath an aromatic sulfo compound. H in which the aromatic group is taken from the class con sisting of benzene, toluene and naphthalene, said sulfo compoundcontaining from 1 to 3 sulfonic" groups, said sulfonic groups having the general formula R where R is taken from the class consisting of OH, NH, NH 1 and alkali metal.

3. A bath in accordance with claim 1 in which the number of acetylenic groups from 1 t0 'the'nu'mber of amino groups present.

4. A bath in'accordance with claim 3 polyamine is diethylenetriamine.-

inwhich the 5 i 6 5. A bath in accordance with claim 3 in which the References Cited in the file of this patent polyamine is ethylencdiamine. UNITED STATES PATENTS 6. A bath in accordance with claim 3 in which the polyaminc is triethylenetetramine. g -"zf 7. A bath in accordance with claim 3 in whi h th 5 0s 6 my 1 polyarninc is tetraethylcnepcntamine. F REI N PATENTS 8. A bath in accordance with claim 3 in which the 499,729 Belgium Dec. 15, 1950 polyamine is pentaethylenehexamine. 146,183 Sweden Feb. 18, 1953 

1. IN A NICKEL PLATING BATH COMPRISING AN AQUEOUS SOLUTION OF A COMPOUND TAKEN FROM THE CLASS CONSISTING A NICKEL SULFATE AND NICKEL CHLORIDE, THE IMPROVEMENT WHICH COMPRISES THE ADDITION OF THE REACTION PRODUCT OF A SOLUBLE ACETYLENIC COMPOUND HAVING FROM 2 TO 15 CARBON ATOMS AND TAKEN FROM THE CLASS CONSISTING OF ACETYLENIC HALIDES AND ACETYLENIC ALCOHOL HALIDES, WITH AN ALKYLENE POLYAMINE HAVING 2 TO 12 AMINO GROUPS, THE ALKYLENE GROUPS HAVING 2 TO 3 CARBON ATOMS, SAID SOLUBLE ACETYLENIC COMPOUND BEING PRESENT IN AN AMOUNT OF FROM .001 G./L. TO 1.3 G./L., SAID PRODUCT CONTAINING AT LEAST ONE CARBON-TO-CARBON TRIPLE BOND AND BEING AN ACETYLENIC POLYAMINE. 